In vitro Thermal and Salt Stability of Pyruvate Kinase Are Increased by Proline Analogues and Trigonelline

Abstract

The nitrogenous compounds N-methyl-L-proline (MP), trans-4-hydroxy-N-methyl-L-proline (MHP) and trigonelline (T), which undergo stress-induced accumulation in some Australian plants, were analysed and compared with proline (P) and glycinebetaine (B) for possible protective roles. The activity of pyruvate kinase (PK), prepared from Zea mays leaves and rabbit muscle, was unaffected even in the presence of 750 mM of the proline analogues. Thus, MP and MHP, like P and B, have the properties to act in vivo as compatible osmotica. T was not as compatible, decreasing enzyme activity 20% at 0.5 M. Like P and B, however, MP, MHP and T all also exhibited protective properties. They increased, in vitro, the thermal stability of PK from both plant and animal sources, and they protected PK (Zea mays) from salt inhibition at two substrate levels. The effect of salt on PK (Zea mays) was substrate dependent; at low phosphoenolpyruvate (PEP) levels, salt inhibited the enzyme activity, while salt effects were less severe in the presence of higher substrate levels. In the presence of high NaCl concentrations, the protective effects of high substrate levels and the compatible solutes seem to be additive. The Km (PEP) value of the plant PK increased in the presence of salt but the effect was ameliorated by the compatible solute MHP.

Stress metabolism. IX. Effect of salt stress on trigonelline accumulation in tomato

“…It is also possible, due to their zwitterionic nature, that trigonelline may have conferred protection to the membranes against the impact of increasing Na + and Cl -concentrations in the meristematic tissues, sustaining cell division and extension despite salt stress. A role of trigonelline in protecting enzymes and conferring thermal stability has also been demonstrated (Shomer-Ilan et al 1991).…”

Characterization of wines from grape varieties through multivariate statistical analysis of 1H NMR spectroscopic data

“…Trigonelline or betaine nicotinate is a neutral chemical compound with a positively charged ammonium ion. Many plant species accumulate trigonelline when subjected to drought and salinity (Shomer-Ilan, Jones, & Paleg, 1991); plants, when exposed to excess salt, accumulate osmoregulators such as GB, proline and trigonelline, to prevent water loss (Tramontano & Jouve, 1997). The high levels of trigonelline in Muscat Bailey A wines may indicate that the Muscat Bailey A grape experienced greater drought stress than the other grape cultivars.…”

Plant Aquaporins: New Perspectives on Water and Nutrient Uptake in Saline Environment

“…Accumulation of ions in the vacuole plays an important role in the response of plants to salinity. To accommodate the ionic balance in the vacuoles, cytoplasm accumulates low-molecular mass compounds that do not interfere with cellular metab-olism (Shomerilan et al, 1991;Rathinasabapathi, 2000;Fernandez-Garcia et al, 2004 b;Martinez-Ballesta et al, 2004). Such compatible solutes or osmoprotectants are highly soluble, and include secondary metabolites, such as quaternary ammonium compounds (glycine betaine), amino acids (proline), and polyols (sorbitol, mannitol), as well as sugars (sucrose, glucose, fructose, trehalose).…”